WASHINGTON (Reuters) – U.S. backers of the Iran nuclear deal are increasingly confident of enough Democratic support to ensure it survives review by Congress, despite fierce opposition by majority Republicans and a massive lobbying drive.

By the time the House of Representatives recessed for the summer last week, no senior Democrat in the chamber had come out formally against the agreement and several central figures, including Minority Leader Nancy Pelosi, were strongly in favor.

Pelosi said she was confident that if, as expected, Republicans pass a “resolution of disapproval” to try to sink the deal, a promised veto of that measure by President Barack Obama would be sustained.

At least 44 Democrats in the House and 13 Democrats in the Senate would have to defy Obama and join Republicans in opposing the deal to get the two-thirds majorities in both chambers needed to override a veto.

“More and more of them (House Democrats) have confirmed to me that they will be there to sustain the veto,” Pelosi told reporters.

The United States was the prime negotiator in the July 14 agreement between world powers and Iran to curtail Tehran’s nuclear program in exchange for lifting sanctions, and its engagement is essential for implementing it.

In the last two weeks, the White House has rolled out its big guns at congressional hearings and private meetings to advocate for the deal, which Obama says is not perfect but is the best way to keep Iran from getting a nuclear bomb.

Powerful pro-Israel lobbying groups that believe it would endanger the Jewish state by empowering Iran have been especially active, although some pro-Israel factions support the deal.

Opponents had hoped influential Democrats would come out against the deal early, to give momentum before the recess.

But despite signs of skepticism, the few Democrats who did openly oppose it, including Representatives Grace Meng and Juan Vargas, are not among those considered influential on the issue.

“That shows the strength of the firewall we have here,” a senior Democratic congressional aide said.

At least 13 Democrats in the Senate and 44 in the House would have to join Republicans in opposing the deal to get the two-thirds majorities in both chambers needed to override a veto.

PRESSURE ON JEWISH LAWMAKERS

To date, no Senate Democrat has formally announced opposition, although many are undecided. A few influential leaders, including number two Democrat Dick Durbin, are strongly in favor.

The Senate recess begins on Friday and both houses return to Washington on Sept. 8. Congress then has until Sept. 17 to accept or reject the pact, which the White House considers one of the major foreign policy initiatives of the Obama presidency.

”I’m encouraged right now,” said Democratic Representative David Price, who has taken on the task of convincing lawmakers from both parties to back the deal. But he cautioned that it is still early in the process.

The pressure has been particularly strong on high-profile Jewish Democrats known as strong supporters of Israel.

The New York Post put Senator Chuck Schumer, the number three Senate Democrat, on its front page, under the headline: “Where’s Chuck? Senator hides from Post’s Iran questions.” Schumer says he has not made up his mind.

Other prominent Jewish Democrats say they are still undecided, including Representative Eliot Engel, the top Democrat on the House Foreign Affairs Committee.

“There’ll be a lot of pressure on Democrats to support the president,” Engel told Reuters.

Engel met with Obama in the Oval Office last Wednesday, and Israeli Ambassador Ron Dermer at the Capitol on Thursday.

He said it would be “very tough” to win over enough Democrats to override the president’s veto. But when asked if he would vote to do so, Engel said, “I’m considering it.”

WASHINGTON (Reuters) – Secretary of State John Kerry told U.S. lawmakers on Tuesday he wanted to set the record straight on the Iran nuclear deal and equated walking away from the agreement to giving Tehran a fast track to a nuclear weapon.

“There are conclusions that have been drawn that don’t in fact match with the reality of what this deal sets forth. And we happily look forward to clarifying that during the course of this hearing,” Kerry told the House of Representatives’ Foreign Affairs Committee.

Joined by Treasury Secretary Jack Lew and Energy Secretary Ernest Moniz, two other members of President Barack Obama’s Cabinet, Kerry was part of the administration’s blitz to coax skeptical lawmakers into supporting the nuclear deal.

The Republican-controlled Congress has until Sept. 17 either to endorse or reject or do nothing about the agreement. Rejection would prevent Obama from waiving most U.S.-imposed sanctions on Tehran, a key component of the deal.

Under the July 14 deal, world powers agreed to lift sanctions on Tehran in return for long-term curbs on a nuclear program the West suspects was aimed at creating an atomic bomb, but which Tehran says is peaceful.

Kerry insisted that walking away from the deal would isolate the United States.

“If we walk away, we walk away alone. Our partners are not going to be with us. Instead, they’ll walk away from the tough multilateral sanctions that brought Iran to the negotiating table in the first place,” Kerry said.

House members signaled the difficulties the administration will face getting Congress on board.

Representative Ed Royce, the Foreign Affairs Committee’s Republican chairman, said the deal would provide Iran with a “cash bonanza,” while weakening Washington’s ability to pressure Tehran.

Representative Eliot Engel, the committee’s top Democrat, also said he saw a number of troublesome issues in the agreement.

Both Republicans and Democrats expressed concern that four Americans are being held in Iranian prisons. Kerry said he was in “direct talks” with Tehran about the detainees.

Others worried about Iran’s support for militants fighting U.S. allies. “They support Hamas, Hezbollah and Houthi, and those are just the organizations that begin with the letter ‘H,’” said Representative Brad Sherman, a California Democrat.

The administration officials insisted the deal was a better way to keep Iran from developing a nuclear weapon than more sanctions or military action.

Kerry, Lew and Moniz also testified in the Senate on Thursday, and Defense Secretary Ash Carter is due to speak to lawmakers later this week.

WASHINGTON, July 28 (Reuters) – Secretary of State John
Kerry told U.S. lawmakers on Tuesday he wanted to set the record
straight on the Iran nuclear deal and equated walking away from
the agreement to giving Tehran a fast track to a nuclear weapon.

“There are conclusions that have been drawn that don’t in
fact match with the reality of what this deal sets forth. And we
happily look forward to clarifying that during the course of
this hearing,” Kerry told the House of Representatives Foreign
Affairs Committee.

Joined by two other members of President Barack Obama’s
cabinet, Treasury Secretary Jack Lew and Energy Secretary Ernest
Moniz, Kerry was part of the Democratic administration’s blitz
to coax lawmakers into supporting the nuclear deal.

Under a law Obama signed in May, the Republican-controlled
Congress has until Sept. 17 either to endorse or reject or do
nothing about the agreement, allowing it to take effect.
Rejection would prevent Obama from waiving most U.S.-imposed
sanctions on Tehran, a key component of the deal.

Kerry, Lew and Moniz also testified in the Senate on
Thursday, and Defense Secretary Ash Carter is among officials
due to speak to lawmakers later this week.

Under the July 14 deal, world powers agreed to lift
sanctions on Tehran in return for long-term curbs on a nuclear
program that the West suspects was aimed at creating an atomic
bomb, but which Tehran says is peaceful.

Kerry insisted that walking away would isolate the United
States.

“If we walk away, we walk away alone. Our partners are not
going to be with us. Instead they’ll walk away from the tough
multilateral sanctions that brought Iran to the negotiating
table in the first place,” Kerry said.

House members signaled the difficulties the administration
will face getting Congress on board.

Representative Ed Royce, the committee’s Republican
chairman, said the deal would provide Tehran with a “cash
bonanza” while weakening Washington’s ability to pressure Iran’s
leaders.

Some Democrats were skeptical also. Representative Eliot
Engel, the committee’s top Democrat, said he saw a number of
troublesome issues in the agreement.

The administration officials insisted the deal was a better
way to keep Iran from developing a nuclear weapon than more
sanctions, or military action.

WASHINGTON (Reuters) – U.S. Secretary of State John Kerry on Thursday mounted a furious counterattack against critics of the Iran nuclear deal, telling skeptical lawmakers it would be fantasy to think the United States could simply “bomb away” Tehran’s atomic know-how.

Testifying publicly before Congress for the first time since world powers reached the landmark accord with Iran last week, America’s top diplomat was confronted head-on by Republican accusations that Iranian negotiators had “fleeced” and “bamboozled” him.

The vitriolic exchanges at the Senate Foreign Relations Committee, which Kerry once chaired, reflected a hardening of positions as Congress opened a 60-day review of the deal considered crucial to its fate.

Iranian hardliners are also trying to undermine the pact, which U.S. ally Israel calls a dire security threat.

Kerry insisted critics of the agreement, which curbs Iran’s nuclear program in return for sanctions relief, are pushing an alternative he dismissed as a “sort of unicorn arrangement involving Iran’s complete capitulation.”

“The fact is that Iran now has extensive experience with nuclear fuel cycle technology,” the former senator said. “We can’t bomb that knowledge away. Nor can we sanction that knowledge away.”

On crutches from a cycling accident, Kerry entered the hearing room to cheers from the anti-war group Code Pink.

Kerry said that if Congress rejects the accord, “the result will be the United States of America walking away from every one of the restrictions we have achieved, and a great big green light for Iran to double the pace of its uranium enrichment.”

“We will have squandered the best chance we have to solve this problem through peaceful means,” he said.

The 4-1/2-hour-long hearing was part of an intense Obama administration push to convince Democrats in particular to back the deal. Treasury Secretary Jack Lew and Energy Secretary Ernest Moniz also testified.

The three cabinet secretaries briefed the full House of Representatives and Senate behind closed doors on Wednesday and met privately with House Democrats after Thursday’s hearing.

Other senior administration officials, including President Barack Obama, have also been talking to undecided lawmakers. About a dozen met with him at the White House on Thursday.

Opening the hearing on a contentious note, the committee’s Republican chairman, Bob Corker, criticized Kerry for the terms he negotiated. “I believe that you’ve been fleeced,” he said.

Another Republican, Jim Risch, said he had been “bamboozled.”

Democratic Senator Barbara Boxer called such accusations “disrespectful and insulting.”

Corker chided Kerry and other administration officials for contending that the only alternative to the accord would be more war in the Middle East, saying the real alternative would be a better deal.

“This is a deal whose survival is not guaranteed beyond the current term of the president,” said Rubio, a 2016 Republican presidential candidate.

Senator Ben Cardin, the top Democrat on the committee, said he has not yet decided how he would vote but that he felt “our negotiators got an awful lot.”

Under a bill Obama reluctantly signed into law in May, Congress has until Sept. 17 to approve or reject the agreement. Republicans hold majorities in both houses of Congress, and many have come out strongly against the pact, which they say will empower Iran and threaten Israel.

Obama, who could boost his presidential legacy from his diplomatic outreach to Iran, needs his fellow Democrats.

If a “disapproval” resolution passes and survives Obama’s veto, he would be unable to waive most of the U.S. sanctions imposed on Iran, which could cripple the nuclear pact.

Responding to criticism that sanctions would be lifted too quickly, Lew said it would not prevent the United States from imposing additional sanctions over issues such as human rights violations if deemed necessary.

Moniz, seeking to counter criticism of “loopholes” in the nuclear inspections regime, said: “I am confident that the technical underpinnings of this deal are solid.”

Seeking to reassure Israel and its U.S. supporters, Kerry said Washington would increase security coordination. Prime Minister Benjamin Netanyahu has expressed concerns that Iran will use unfrozen assets to increase funding and weapons to militant groups such as Hamas and Hezbollah.

Kerry said the Iran deal carried the “real potential” for change in the Middle East but acknowledged it “does not end the possibility of a confrontation with Iran.”

WASHINGTON (Reuters) – U.S. Secretary of State John Kerry on Thursday mounted a furious counterattack against critics of the Iran nuclear deal, telling sceptical lawmakers it would be fantasy to think the United States could simply “bomb away” Tehran’s atomic know-how.

Testifying before Congress for the first time since world powers reached the landmark accord with Iran last week, America’s top diplomat was confronted head-on by Republican accusations that Iranian negotiators had “fleeced” and “bamboozled” him.

The vitriolic exchanges on Capitol Hill reflected a hardening of positions as Congress opened a 60-day review of the deal considered crucial to its fate.

Iranian hardliners are also trying to undermine the pact, and U.S. ally Israel has condemned it as a dire security threat.

Kerry insisted that critics of the deal, which curbs Iran’s nuclear programme in return for sanctions relief, are pushing an unrealistic alternative that he dismissed as a “sort of unicorn arrangement involving Iran’s complete capitulation.”

Kerry said that if Congress rejects the agreement reached in Vienna, “the result will be the United States of America walking away from every one of the restrictions we have achieved and a great big green light for Iran to double the pace of its uranium enrichment.”

“We will have squandered the best chance we have to solve this problem through peaceful means,” he said.

The United States, Russia, China, Britain, France, Germany and the European Union signed the deal with Iran. Washington suspects Tehran of having worked in the past to build nuclear weapons but Iran says its program is peaceful.

Opening the hearing on a contentious note, the committee’s Republican chairman, Bob Corker, criticized Kerry for the terms he negotiated. “I believe that you’ve been fleeced,” he said.

Democratic Senator Barbara Boxer later called such accusations “disrespectful and insulting.” Corker then made clear he had not intended any personal offence to Kerry.

But Corker chided Kerry and other administration officials for their line of argument that the only alternative to the accord would be more war in the Middle East, saying that the real alternative would be a better deal.

“This is a deal whose survival is not guaranteed beyond the current term of the president,” said Rubio, a 2016 Republican presidential candidate.

Senator Ben Cardin, the top Democrat on the committee, said he has not yet decided how he would vote but that he felt that “our negotiators got an awful lot.”

Under a bill Obama reluctantly signed into law in May, Congress has until Sept. 17 to approve or reject the agreement. Republicans hold majorities in both houses of Congress, and many have come out strongly against the pact, which they say will empower Iran and threaten Israel.

Obama, who could gain a boost to his presidential legacy from his diplomatic outreach to U.S. foe Iran, needs to convince as many of his fellow Democrats as possible to back the deal.

If a “disapproval” resolution passes and survives Obama’s veto, he would be unable to waive most of the U.S. sanctions imposed on Iran, which could cripple the nuclear pact.

Treasury Secretary Jack Lew and Energy Secretary Ernest Moniz also testified as part of an effort to sell the deal to lawmakers, as well as to the American public and uneasy Middle East allies.

Responding to criticism that the agreement lifts sanctions too fast, Lew said it would not prevent the United States from imposing additional sanctions over issues such as human rights violations if deemed necessary.

Moniz, seeking to counter criticism that loopholes in international inspection will allow Iran to cheat, told lawmakers: “I am confident that the technical underpinnings of this deal are solid.”

Seeking to reassure Israel and its U.S. supporters, Kerry said Washington would increase security coordination. Prime Minister Benjamin Netanyahu has expressed concerns that Iran will use unfrozen assets to increase funding and weapons to militant groups such as Hamas and Hezbollah.

Kerry said the Iran deal carried the “real potential” for change in the volatile Middle East but acknowledged it “does not end the possibility of a confrontation with Iran.”

WASHINGTON/DUBAI, July 23 (Reuters) – U.S. Secretary of
State John Kerry and Iranian President Hassan Rouhani both
counter-attacked on Thursday against conservatives at home who
are trying to block last week’s nuclear deal.

In Washington, Kerry told sceptical lawmakers that rejection
of the accord would give Tehran “a great big green light” to
accelerate its atomic programme.

Rouhani, elected two years ago on a promise to reduce the
international isolation of the country of nearly 80 million
people, defended the agreement following criticism from the
Revolutionary Guards and conservative lawmakers that it
endangers Iran’s security.

In an unlikely common cause, the U.S. and Iranian
governments need to sell the agreement to domestic doubters if
it is ever to achieve both sides’ respective aims – curbing
Tehran’s nuclear programme in return for an easing of sanctions
which have badly hurt the Iranian economy.

Testifying to Congress, Kerry fought back against
accusations by a senior Republican that he had been “fleeced” by
Iranian negotiators in the final round of the Vienna talks.

He warned of the consequences of rejecting the deal between
Tehran and world powers including the United States.

“We will have squandered the best chance we have to solve
this problem through peaceful means,” he told the Senate Foreign
Relations Committee.

“The fact is that Iran now has extensive experience with
nuclear fuel cycle technology,” he said as Congress began a
60-day review of the deal to decide whether to support or reject
it. “We can’t bomb that knowledge away. Nor can we sanction that
knowledge away.”

Opening the hearing, the committee’s Republican chairman,
Bob Corker, attacked Kerry over the terms he secured in Vienna.
“I believe that you’ve been fleeced,” said Corker.

Treasury Secretary Jack Lew also said the agreement would
not prevent the United States from imposing additional sanctions
on Iran over issues such as human rights violations – a
Congressional concern – if it felt this was necessary.

Despite the rough ride in the Republican-controlled
Congress, President Barack Obama says he will veto any attempt
to block the agreement. Overriding such a veto would require a
two-thirds majority in both houses, which means dozens of
Obama’s fellow Democrats would have to reject a signature
achievement of their president to kill the deal, seen as an
unlikely prospect.

Opposition is similarly stiff in Iran, even though many
people there hope the accord will deliver prosperity by bringing
an end to the sanctions and the country’s economic isolation.

Supreme Leader Ayatollah Ali Khamenei, a conservative cleric
whose authority supersedes that of the elected president
Rouhani, has yet to deliver a final verdict on the deal.

Conservative members of parliament and Revolutionary Guards
commanders say the deal has breached conditions set by Khamenei,
and want changes.

“NEVER THREATEN AN IRANIAN”

Rouhani rejected such doubts. “The agreement conveyed this
message to the world: Never threaten an Iranian anymore,” he
said in a speech broadcast live on television.

“This agreement sent the message to the world that the most
difficult and complex international issues can be resolved
through negotiations. Iran’s path is a path of moderation.”

Chiding the critics, Rouhani said he had noted some Iranian
officials were “scrutinising one by one the terms of the deal”
and a subsequent resolution endorsing it which the United
Nations Security Council passed on Monday.

“That’s good but what has happened is more valuable and more
significant than that,” he said.

Many analysts see the chance of the Iranian leadership
eventually rejecting the accord as small, since Tehran needs the
lifting of sanctions to help its isolated economy.

The debate over the details largely reflects internal
rivalries in Iran’s cumbersome dual system of clerical and
republican rule, in which factions jostle to gain maximum
benefit from the deal while deflecting blame.

Iran’s procedures for ratifying the accord are not known in
any detail. Whatever the eventual role of bodies such as
parliament or the National Security Council, the deal will have
to be approved by Khamenei, the country’s highest authority.

Kerry also has to sell the agreement to U.S. allies in the
Middle East. Israel is strongly and publicly opposed, and
Washington’s Sunni Muslim-ruled Arab allies, led by Saudi
Arabia, are also wary about an arrangement that would benefit
their rival, Shi’ite Iran.

In Jeddah, Saudi Foreign Minister Adel al-Jubeir told
reporters that his country hoped the deal would curb rather than
expand “Iran’s interference in the region’s affairs”.

“We hope that Iran will make use of the deal’s fruits to
re-build their country and to improve their people’s quality of
living, not to use it to conduct more subversion in the region.”

Jubeir added that any agreement should guarantee Iran’s
inability to get nuclear weapons and allow inspection of “all
locations including the military locations”.

Iran denies the nuclear programme aims to produce weapons.

The Revolutionary Guards do not want any inspection of their
military sites and say they will not bow to any restriction on
Iran’s missile programme and arms imports. The deal leaves U.N.
restrictions on missiles and weapons in place for several years.

The main financial sanctions, which have severely hurt
Iran’s economy since 2012 after they were tightened by the
United States and European Union, are unlikely to be removed
until next year, as nuclear inspectors must first confirm Iran
is complying with the deal.

But Minister of Industry, Mines and Trade Mohammad Reza
Nematzadeh outlined plans to rebuild Iran’s main industries and
trade relationships following the deal, saying it was targeting
oil and gas projects worth $185 billion by 2020.

WASHINGTON (Reuters) – U.S. Secretary of State John Kerry mounted a furious counterattack against critics of the Iran nuclear deal on Thursday, telling skeptical lawmakers that rejection of the accord would give Tehran “a great big green light” to swiftly accelerate its atomic program.

Testifying before Congress for the first time since Iran and world powers reached the deal last week, Kerry fought back against accusations by a senior Republican that America’s top diplomat was “fleeced” by Iranian negotiators in the final round of the Vienna talks.

He insisted that those who oppose the deal, which curbs Iran’s nuclear program in return for sanctions relief, are pushing an unrealistic alternative that he dismissed as a “sort of unicorn arrangement involving Iran’s complete capitulation.”

Kerry said that if Congress turns thumbs down on the deal, “the result will be the United States of America walking away from every one of the restrictions we have achieved.”

“We will have squandered the best chance we have to solve this problem through peaceful means,” he said as Congress began a 60-day review of the deal to decide whether to support or reject it.

Opening the hearing, the committee’s Republican chairman, Bob Corker, offered scathing criticism of Kerry for the terms he secured in negotiating the deal. “Not unlike a hotel guest that leaves only with a hotel bathrobe on his back, I believe that you’ve been fleeced,” he said.

Corker chided Kerry and other administration officials for their line of argument that the only alternative to the Iran deal would be more war in the Middle East, saying that the real alternative would be a better deal.

U.S. Senator Ben Cardin, the top Democrat on the committee, said he has not yet decided how he would vote but said he felt U.S. negotiators had made significant progress.

WASHINGTON (Reuters) – Republican and Democratic senators were to introduce amendments to a Senate bill on Thursday that would end some major U.S. restrictions on travel and trade with Cuba, according to documents seen by Reuters.

The measures being put forward at the Senate Appropriations Committee, if approved, would be the first legislation to make it through any congressional committee to facilitate President Barack Obama’s push to normalize relations with Cuba.

Republican Senator Jerry Moran was to introduce an amendment to the Senate Financial Services appropriations bill to end the prohibition on most U.S. citizens’ travel to the Communist-ruled island.

Republican Senator John Boozman was preparing to offer an amendment to change current law prohibiting Americans from providing credit for the sale of U.S. agricultural commodities.

His measure would allow private financing, so sales of agricultural commodities by U.S. exporters do not have to be paid in cash.

Senator Jon Tester, a Democrat, was due to offer an amendment eliminating a law barring any ship that has docked in Cuba from loading or unloading any freight in the United States for 180 days.

The amendments all have bipartisan support and backers say they are expected to pass in committee.

By introducing the measures as amendments to the larger appropriations bill, the proposers intend to make them more difficult to block. If they are adopted by the committee, the full Senate would have to reject the entire financial services bill to stop them.

To become law, a version of the bill with the amendments also would have to pass the House of Representatives, which would be more likely if it draws strong support in the Senate.

Obama and Cuban President Raul Castro announced on Dec. 17 that they had agreed to move toward normal relations between the former Cold War foes for the first time in half a century.

As part of the push, Cuba opened its embassy in Washington on Monday as the countries restored diplomatic relations.

But the broader, half-century-old U.S. trade embargo remains in place and only Congress can lift it – something majority Republicans are unlikely to do.

Despite that, lawmakers, including many from states with significant agriculture or shipping business like Moran’s Kansas, Boozman’s Arkansas and Tester’s Montana, have pushed to ease the restrictions.

But such moves have run into stiff opposition from high-profile Cuban-American lawmakers backed by the Republican leaders of the Senate and House.

WASHINGTON (Reuters) – U.S. lawmakers skeptical about the nuclear deal with Iran promised to press senior Obama administration officials to make more information about it public at a Senate hearing on Thursday as Congress begins its two-month review of the agreement.

Secretary of State John Kerry, Treasury Secretary Jack Lew and Energy Secretary Ernest Moniz will testify before the Senate Foreign Relations Committee, the first such public appearance by the cabinet officials since the deal was announced on July 14.

They briefed the entire Senate and House of Representatives in separate closed-door sessions on Wednesday, and administration officials have held a series of private telephone conversations and meetings with lawmakers.

Among other issues, lawmakers said they wanted more information about the timing of sanctions relief and ability to “snap back” sanctions if Iran cheats, clarity on the timing of inspections and more answers about how much money would go to Iran.

“We have leverage, but in nine months, they’ll have their cash and all the sanctions will be relieved. People will be in there signing contracts, and then the leverage sort of shifts to them,” said Senator Bob Corker, the Republican chairman of the Foreign Relations Committee.

Corker has said he is skeptical about the agreement, but would wait until he knows more before deciding whether to vote against the deal.

Ben Cardin, the top Democrat on the panel, said the closed-door briefing had been useful but questions remained. “There are many areas of concern that we want to get clarified,” he said.

Cardin is one of many Democrats who have not yet decided how they would vote on the deal.

Under a bill President Barack Obama signed into law in May, Congress has until Sept. 17 to approve or reject the agreement, in which Iran agreed to rein in its nuclear program in exchange for sanctions relief.

With many Republicans lining up to oppose it, Obama needs to convince as many of his fellow Democrats as possible to back the deal. If a disapproval resolution passes Congress and survives a veto, Obama would be unable to waive most of the U.S. sanctions imposed on Iran, which could cripple the nuclear pact.

WASHINGTON (Reuters) – Top Republicans vowed on Wednesday to do their utmost to scrap President Barack Obama’s nuclear deal with Iran as the biggest pro-Israel lobby geared up for an all-out campaign next week to pressure wary lawmakers into rejecting the agreement.

A bigger push against last week’s historic accord in Vienna was being met with a counter-offensive by senior Obama administration officials, who briefed groups of lawmakers in closed-door sessions on Wednesday and will defend the deal in a congressional hearing on Thursday.

As Congress opened a 60-day review of the deal, U.S. House of Representatives Speaker John Boehner, the top congressional Republican, told reporters: “Because a bad deal threatens the security of the American people, we’re going to do everything possible to stop it.”

The most influential pro-Israel group, the American Israel Public Affairs Committee (AIPAC), planned to deploy hundreds of lobbyists on Capitol Hill next Wednesday and Thursday to try to convince lawmakers, especially wavering or undecided Democrats, to vote against the deal, according to an official in the pro-Israel camp.

AIPAC will also run a national campaign of television commercials already under way and sponsored by allied groups such as Citizens for a Nuclear Free Iran, U.S. pro-Israel sources said. The groups are expected to spend upwards of $20 million, one of the sources said.

Congress has until Sept. 17 to decide whether to approve or reject the agreement between Iran and world powers to rein in Iran’s nuclear programme in return for sanctions relief.

Republicans control majorities in both houses of Congress, and many have already come out strongly against the pact, which they say will empower Iran and threaten U.S. ally Israel.

But if Congress passes a resolution disapproving of the deal, dozens of Democrats would have to vote with them to override the Democratic president’s threatened veto, something that would be hard for the Republicans to achieve.

Nancy Pelosi, the Democrats’ leader in the House, has come out strongly in favour of it. Among the senior Democrats who pro-Israel lobbyists hope to win over is New York Sen. Chuck Schumer, a strong advocate for Israel’s security who has yet to state his position on the deal.

“It’s a steep climb but not an impossible climb,” the pro-Israel group official said of the coming campaign.

Hardline opponents of the deal in the pro-Israel camp believe wavering lawmakers can be swayed by detailed arguments about what they see as loopholes, especially for international inspections.

In addition, pressure from AIPAC, which boasts 100,000 members and whose election endorsement is coveted by many lawmakers, could create nervousness among members of Congress up for re-election.

At the same time, J Street, a smaller liberal pro-Israel group, is urging supporters to lobby their lawmakers to support the Iran deal.

Secretary of State John Kerry told reporters as he walked into a close-door meeting with lawmakers that the deal “will make the region, our friends and allies, safer. It will make the world safer … in the absence of any viable alternative.”

Kerry, Treasury Secretary Jack Lew and Energy Secretary Ernest Moniz are due to testify on Thursday to the Senate Foreign Relations Committee.